1. Field of the Invention
The present invention relates to a refill case in which staples for stapling paper sheets are accommodated in straight states before formation.
2. Related Art
An electric stapler is so constituted as to be capable of attaching and detaching a staple cartridge. The staple cartridge is so constituted as to be capable of attaching and detaching a refill case in which staple-sheets, each of which is formed by connecting straight staple members with an adhesive in a sheet shape, are accommodated in a stacking manner. The refill case includes a staple pressing member which is arranged inside an accommodating part and presses a top of the accommodated staple-sheets, and return-preventing claws formed at left and right ends of the staple pressing member. These return-preventing claws are provided so as to be capable of locking in locking saw-toothed portions (return-preventing grooves), each having a saw-toothed cross section, which are formed in left and right inner walls of the accommodating part and extending along a stacking direction of the staple-sheets (Patent Document 1).
To the contrary, the staple cartridge includes a feeding path which is connected to a leading-out port from which the lowermost staple-sheet in the accommodating part of the refill case is led out, and a feeding means which leads out the lowermost staple-sheet in turn to the feeding path and feeds the led-out staple-sheet to a drive-out part side. In the feeding means, a feeding pawl is formed obliquely upward. The feeding pawl is so constituted as to feed out the staple-sheet in a state locked to a groove between front and rear staples on a bottom of the lowermost staple-sheet. Accordingly, when the staple-sheet is moved in the feeding direction, the feeding pawl acts so as to stick up the staple-sheet obliquely upward
[Patent Document 1] US2008/0083805
However, in a device which adopts, as a feeding mechanism for feeding a staple-sheet to a drive-out part, such the structure that a feeding pawl is arranged obliquely to the staple-sheet, a leading end of a feeding pawl is engaged with a groove between adjacent staple members, and the feeding pawl feeds the staple-sheet so as to stick up the staple-sheet obliquely upward so that the leading end is disengaged, there is no problem in case that the number of the staple-sheets is large and the whole weight of the staple-sheets is heavy. However, for example, in case that only the last one sheet remains, when this staple-sheet is tried to be fed, there is possibility that the staple-sheet floats when stuck up by the feeding pawl and a return-preventing claw of a staple pressing member which presses the staple-sheets unlocks from a return-preventing groove. The unlocked return-preventing claw floats and engages with a peak of a return-preventing groove located immediately above the return-preventing groove. The floating amount of the staple pressing member at this time corresponds to the distance between the adjacent teeth, that is, a pitch. Therefore, there is fear that the feeding paw might disengage from the floating staple-sheet and poor feeding might be produced.
Further, when the refill case is conveyed, the return-preventing claw is liable to unlock from the locking saw-toothed portion due to large vibration. Further, in case that the return-preventing claw has unlocked, since the staple-sheet floats greatly, there is possibility that the adhesive bonding the staple members peels off at a part of the staple-sheet, the staple-sheet breaks and the connected staple members are separated. Further, also when the stapler is operated or an attaching table to which the stapler is attached moves, there is possibility that the vibration is produced in the refill case and the similar disadvantage is produced.
In order to solve these problems, it is thought to make a pitch between the teeth of the return-preventing groove small. However, since the staple-sheet is considerably thin, it is necessary to make the pitch between the teeth of the locking saw-toothed portion smaller than the thickness of the staple-sheet. In case that the refill case is formed of synthetic resin, since there is a limit in forming, it's not to say that the above pitch can be freely made small. There is a limit in making the pitch small.